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					Using Kanban Techniques to Control Incremental Development

Jeff Patton
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In this short talk we’ll cover:

1. What is a Kanban System and how does it apply to software development?
2. How to set up a development team Kanban System 3. Applying Lean thinking to software development

看板 – Kanban cards limit excess work in progress
看板 – Kanban literally means “visual card,” “signboard,” or “billboard.” Toyota originally used Kanban cards to limit the amount of inventory tied up in “work in progress” on a manufacturing floor Not only is excess inventory waste, time spent producing it is time that could be expended elsewhere Kanban cards act as a form of “currency” representing how WIP is allowed in a system.

Kanban simulation
Let’s simulate a simple process, then see if we can improve it by adding a Kanban system.

I’ll need 5 volunteers to manufacture the latest in high-tech aircraft

Why use Kanban in Software Development?
(we’re not building aircraft – or anything tangible really)


Time-boxed iterative development has challenges
Common problems include: •Short time-boxes give more frequent opportunity to measure progress and inspect software but force development items to be smaller •Smaller development items are often too small to be valuable and difficult to identify •Quality of requirements suffers as analysts rush to prepare for upcoming cycles •Quality of current development suffers when busy analysts are unable to inspect software or answer questions during development •Quality often suffers as testers race to complete work late in the development time-box 6

Inside an iteration, effort across roles is uneven

Development work often continues throughout a cycle while testing starts late and never seems to get enough time 7

Using a Kanban approach in software drops timeboxed iterations in favor of focusing on continuous flow.

How to set up a simple Kanban system for a software development team.


1. Define a work process flow

This simple process flow has the steps: 1.elaboration & acceptance criteria 2.development 3.test 4.deployment

Look at the typical flow for features, stories, or work packages and describe typical process steps


2. Lay out a visual Kanban board
Place an expedite track above the main left to right queue

Place “done and waiting” queues between each work queue (in this example they’re placed below)

Place a goals column on the left, then a waiting queue, the process steps, and a final “done” column to the right 11

3. Decide on limits for items in queue and work in progress

This board uses painters tape to indicate available “slots” for work in progress

A good limit is a factor of the number of people in a role that can work on an item in a given process step. Start with number of people * 1.5

4. Place prioritized goals on the left column of the board

Having goals visible: •promotes focus •helps us prioritize •helps us manage feature scope & requirements

A good goal describes the outcome we hope to achieve after software ships. Goals help keep focus on the larger outcome.

5. Start the board by placing stories or features in queue

Product owners manage the waiting queue

Mark on the story or feature card the date it entered the queue. This begins our measurement of cycle time.

6. Move features through the process flow as work is completed

As the story enters the first process step, mark that date on the card. This is the start date. As it’s finished, mark that date on the card. This 15 is the finish date.

7. Use the dates on the cards to calculate cycle time

Cycle time = finish date – start date The average cycle time from the date the item enters the board is the wait time from this point in the queue

Use average cycle time to set wait times from different points on the board. Pay attention to flow and bottlenecks: relieving bottlenecks as 16 quickly as possible.

Display and manage cycle times
Disneyland’s public display of cycle-times

Reduce the number of Kanban slots allowed until cycle time remains unchanged Reduce the size of development items •Work in progress is actually the number of items * the average size of items

Identify and act on bottlenecks immediately
•Relieve repeated bottlenecks by changing the number and types of people in each role and cross training 17

Kanban Boards


Kanban Boards


Kanban Boards


Kanban Boards


Kanban Boards


Explode large process steps into tasks to improve visibility
When a feature, user story, or work item is large:
 Takes longer than a couple days to complete  Requires that multiple people collaborate on its completion

Decompose that step into cards to track independently
Feature to develop Tasks in progress Tasks complete Feature complete

Tasks in queue


Kanban Board with Task Decomposition


Use cumulative flow diagrams to visualize work in progress

Use cumulative flow diagrams to visualize work in progress

Keep time-boxed product and process inspection
Keep regular time-boxes in your process as a cue for product inspection: •Evaluate the quality of the growing product from a functional, engineering, and user experience perspective Evaluate your pace of development: •Look at the number of development items completed relative to goals •Look at the average cycle time per development item •Calculate the ratio of developer days per completed item. Use this ratio to estimate the completion time for undeveloped items •Adjust your development plan as necessary Evaluate and adjust the process you’re using •Use a process reflection session to identify changes you could make to improve your product or pace
Ending cycles right:

Begin looking at your process using Lean thinking

Cockburn’s Software Engineering in the 21st Century:


Since we’re engaged in “knowledge work” look at the cycle time of validated decisions, or knowledge

Cockburn’s Software Engineering in the 21st Century:


Often the feedback loop is overlooked – it’s the invisible backed-up queue

Cockburn’s Software Engineering in the 21st Century:


Setting up a simple Kanban system starts to focus the team on the cycle-time of delivered work and gives a way to detect and begin to resolve bottlenecks


Kanban References:
• Anderson, Kanban in Action: on.html • Hiranabe, Kanban Applied to Software Development: from Agile to Lean: • Ladas, Scrumban - Essays on Kanban Systems for Lean Software Development: • Ladas, Scrum-ban: • Belshee, Naked Planning, Kanban Simplified:


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